Telephone signal transmitter



May 23, 1950 W. A. MARRISON TELEPHONE SIGNAL TRANSMITTER Filed Dec. 5,1947v 5 Sheets-Sheet l @y (iwf/M ATTORNEY May 23, l950 W. A. MARRISON2,508,526

TELEPHONE SIGNAL TRANSMITTER Filed Dec. 5, 1947 s sheets-.sheet 2/NVE/VTOR W A. MARR/50N ATTORNEY May 23, 1950 w. A. MARRISON 2,508,526

TELEPHONE SIGNAL TRANSMITTER Filed Deo. 5, 1947 5 Sheets-Sheet '3ATTORNEY Patented May TELEPHONE SIGNAL TRANSMITTER Warren A. Marrson,Maplewood, N. J., assignor to Bell Telephone Laboratories, Incorporated,New York, N. Y., a corporation of New York Application December 5, 1947,Serial No. 789,881

12 Claims. 1

This invention relates Ato signal transmitters and more particularly toa selective signaling transmitter in` which the selectivity is obtainedby sending coded pulse signals simultaneously over a plurality ofdifferent frequencies.

A feature of the present invention is a signal transmitter which cantransmit in a simple manner a far greater number of different signalcombinations than transmitters now in use.

Another feature of the present invention is a transmitter composed of anumber of simultaneously operating generators, with each generatoroperative at a different frequency.

A further feature of the invention is a transmitter in which pulseshaving diiferent combinations of time relationship to each other may beobtained from the generators and combined to form a composite signal.

Still another feature of the subject invention is a signal transmitterin which the code to be transmitted may be selected merely by rotatingdiscs before the transmitter is operated.

A still further feature of this invention is a signal transmitter withvisual means for indicating the code that is transmitted.

Another feature of the subject invention is a signal transmitter whichtransmits, along with its coded signal, a distinctive signal foridentifying itself as the calling transmitter.

A still further feature of the present invention is a transmitter inwhich a warning signal is first transmitted to indicate that the codedsignals are about to follow.

Other features of the present invention will become apparent from thefollowing detailed discussion, when taken in conjunction with theaccompanying drawings.

In accordance with the subject invention, a selective signalingtransmitter is contemplated which will be able to send out millions, ifnot bi1- lions, of different signal combinations. This is effected bymeans of a number of generators which revolve at the same rate becauseconnected to the same shaft, but which have different frequencies as aresult oi the fact that their stator pole elements have a differentnumber of notches cut in them. Each generator is equipped with at leastone set of adjustable stator pole elements containing a number ofstators in each set and these adjustable stators are normally positionedso that they will have no influence on the rotors when the rotors turn.However, if two of the stator poles in each set are moved towards therotor so as to induce a current in the rotor winding as the rotor turns,a distinctive code signal may be obtained from each set of stators. Bycombining the code signals from all of the sets of stators on thegenerators, it may be seen that an extremely great number of possiblesignal combinations may be obtained. The combinations are distinctivebecause as the generator rotates all of the individual code signalsbeing transmitted at one time have different frequencies and these arein turn followed by other groups of code signals which, although havingthe same frequencies as the individual code signals in the `first groupof transmitted signals, are nevertheless distinguishable from thesesignals by the separation in time.

The particular combination of adjustable pole elements in a set that arepositioned close to the rotor is determined by the rotary position of acoded disc. This disc has irregularities extending around its peripheryin such manner that no matter how the disc is turned some combination oftwo stator pole elements will be selected to move towards the rotor. Thedisc is turned to the correct position before the transmitter starts tooperate by rotating cylinders coupled to the discs, the rotation of thecylinders being facilitated by the fact that the cylinders extend abovethe transmitter chassis partially protruding through slots cut in thecover. Coded identications are provided on the periphery of thecylinders so that a particular identification can be selected when theidentification can be seen from a point directly above the cylinder. Theselection takes place through the action of feeler levers, which areattached at one end to the adjustable pole elements and at the other endare positioned close to the periphery of the code disc. When thetransmitter is about to be operated, the feeler levers are actuated tomove towards the code disc and make contact with its periphery. A feelerlever which encounters a raised irregularity on the periphery ispositioned differently from the other levers which rest in recesses ofthe code disc, This difference in position results in certain statorelements being located closer to the rotor than other stator elements inthe set.

In addition to the pole elements described above, each generator isprovided with an additional set of stator pole elements which unlikethose described above, are not adjustable in position but are preset.Two of the stator elements from each of these sets are permanentlypositioned near their respective rotors while the other elements arenot. Thus, as the rotors turn, a signal having a constant codeindication is obtained from each generator and the combination of theseconstant signals may serve as an identication for the callingtransmitter, provided that each transmitter has a distinctivecombination of xed code signals. Further pole elements may also beprovided on the stator of each generator to give a warning indication tothe central oiiice, when the generators start to rotate, that a codedsignal is about to be transmitted. These pole elements should bearranged to give a signal of a different pattern than those of thecalling and identifying signals. For example, whereas two out of eachset of pole elements are selected for the calling and identifyingsignals, a distinctive start signal might result if three pole elementsin juxtaposition to each other on each generator were positioned neartheir respective rotors Referring now to the accompanying drawings:

Fig. 1 is a simplified illustration of one of the generators comprisingthe transmitter, showing the associated mechanisms which operate toprepare the generator for the transmission of a particular code;

Fig. 2 is a view of the same generator as that shown in Fig. l after theassociated mechanisms have operated on the generator;

Fig. 3 is a side view with respect to Figs. l and 2, showing therelationship of the generators and of the associated mechanisms in thecomplete transmitter;

Fig. 4 shows how the transmitter might appear when used as a subscribersset in a telephone system;

Fig. 5 is a table of the different combinations that may result if atwo-out-of-six selection is used as the coded pattern; and

Figs. 6 and 7 show how the different combinations of Fig. 5 might bearranged in an overlapping fashion around a code disc used to prepare agenerator ior the transmission of a particular code.

In Fig. l, to which reference is now had, the means are shown wherebycoded information is conveyed to the stator pole elements of one of thegenerators. These means include the adjustable stator pole elements IGIthrough I2, inclusive, arranged in two sets containing six stator poleelements in each set; the pole elements IIS through II'I, inclusive,serving to transmit a signal by which the calling transmitter maybeidentiiied; the pole elements |I8, ||9 and |20 as the means forconveying a start signal; the coded disc |2| which is oriented intoposition for the transmission of a desired signal by revolving thecylinder |22 about shaft |65; and the feeler levers |23 through |34,inclusive, which act to move their respective stator pole elementstowards the rotor |35 of the generator |00 so that a desired code signalmay be transmitted. The motor |00 is mounted upon the base |36 and thisis in turn fastened to the chassis |31 by means of the bolts |38. Sincethe rotor pole element |63, which is composed of magnetic material issurrounded by a coil |39, a voltage will be induced in the coil as itrotates past any stator pole elements which have been positioned closeto the rotor pole |53. After passing through the winding |39 and theslip ring |40 to the brush |4|, this generated voltage will appear atthe output terminals of the transmitter. The stator ring |64 is alsofastened to the transmitter chassis |31 by means of the supportingplates |42, these plates being welded to the chassis |31 at one end andsecured to the stator ring by means of the bolts |43 at the other end.

As shown in Fig. l, four sets of stator pole elements are located aroundthe periphery of the stator ring |64. The lbottom of these sets containsthe ve pole elements ||3 through IIl', inclusive, with the poles ||3 andIIB shown in closer proximity to the axis of rotation of the rotor |35,where they will be magnetically coupled to the rotor pole |63 as therotor |35 rotates. rEhe bolts |44 serve to clamp the stator poles I I3through ill in the positions shown. Because ol' the action of the bolts|44, the two-out-of-iive pattern of the bottom set of stator poleelements will remain fixed until changed manually. It may be seen thatii each generator comprising the transmitter has iive pole elements inits bottom set and two elements out of the five in the set arepositioned close to the rotor, a large number of diierent combinationswill exist when the patterns from all the generators in a transmitterare combined. For example, two-out-of-ilve patterns on a transmittercomprising four generators would yield ten different combinations foreach generator and a total of (l0)4 or 10,000 different combinations forthe complete transmitter. A distinctive combination, then, could serveas the means by which a calling transmitter could be identified. Itshould be noted that a different number than ve pole elements might beused as a set and likewise a diierent number than two pcie elementscould be chosen from the set as the basis for distinctive combinationsor" pole elements. For example, a three-out-of-iive combination might beused, and this would again yield 10,000 differenty combinations if thetransmitters were composed oi four generators. Or a two-outof-sixcombination might yield fifteen different combinations for onegenerator, and for a transmitter of four generators the total would be(15)4 or 50,625 combinations. Again, if the number of generators werechanged, the number of possible combinations would change. As anillustration, a two-out-of-ve combination with live generators insteadof four would yield ten times as many combinations as with fourgenerators or a total of' 100,000 different possibilities.

Although the bottom set of stator `pole elements is positioned in aconstant relationship for as long a time as the bolts |44 are tight, thetwo side sets comprising the stator poles |l| through I|2, inclusive,are not rigidly clamped by bolts and thus these pole elements are freeto move in their slots, as the slot |45 in the stator element iI. rTheseslots are so located that the stator elements are free to move only in ahorizontal drection towards or away from the rotor |35. Each of theelements IDI throughv II2, inclusive, is fastened to a separate feelerlever at, the end furthest away from the rotor |35 and it is theselevers which push their respective stator elements into position toinfluence the rotor as it rotates. Thus, for example, the stator element10| is fastened to the feeler lever |23 by means of the pivot |46;likewise, the feeler levers |24 through |34, inclusive, are fastened tothe stator elements 522 through ||2, respectively. These levers are alsofastened to two rack gears |4`| and |48 at a point above theirconnections to the stator elements, the levers |23 through |28 beingfastened to the rack gear |41 and the other levers being fastened to therack gear |48. The connections are by shafts |49 and |50, respectively,as will be explained more fully in connection with the discussion ofFig. 3. Like the stator elements, the rack gears |41 and |48 are free tomove. since they are |152 extend through the gears. lment of the rackgears |41 and |48 takes place, vcertain of the stator elements are movedtowards '5 slotted at the points where the shafts and When this movetherotor, as will be described below.

Whereas the feeler levers |23 through |28 and |29 through |34 arefastened at their bottom ends .to their respective stator elements,these levers are positioned close to the peripheries of the discs |2|and 20|, respectively at their top and, the disc 20| being shown in Fig.2 by cutting away part of the disc |2|. The levers |23 through |20,inclusive, are so constructed that a prong-like feeler extends from eachlever to a point close tothe disc |2| likewise, a prong-like feelerextends from each of the levers |29 through |34, inclusive, to theperiphery of the disc 20|, which lies behindthe dise |2| so that itcannot be seen in Fig. l. Thus, when the rack gears |41 and |48 'aremoved the length of their slots |53 and |54,

respectively, the feeler levers 'are pivoted about the shafts |49 and|50 so that their feelers come into contact with the periphery of thecode disc. Wherever a feeler touches one of the raised portionsextending out from the periphery of the discs |2| and 20|, the statorelement associated with the particular Ifeeler lever will be pushedtowards the rotor |35, as shown in Fig. 2. Considering the groupcomprising the levers |23 through |28, inclusive, the reason for thismay be seen in the fact that the raised portions of the code wheel causethe selective feelers to adopt a position to the right of the feelerswhich touch the recessed portions of the periphery and as a result ofthe lever action of the feeler levers about the shaft |40, the bottomportions of the selective feeler levers will adopt a position to theleit of the other levers, thus moving the associated stator elements tothe left also. Movement to the left of stator elements in the setcomprising the elements |0| through |06, inclusive, results in theelements being positioned near the rotor |35. Fig. 2 shows the feelerson the levers |23 and |25 in contact with raised portions of the dise i2l, thus causing the pole elements |0| and |00 to move close to the rotor|35. In like manner, those levers in the set comprising the levers |25through |34 whose feelers touch raised portions of the code disc 20|will pivot about the shaft |50 and move the associated stator elementstowards the rotor |35. In Fig. 2, the levers l 32 and |33 touch raisedportions on the disc 20| 'thus causing the stator pole elements I I0 andl I to move close enough to the rotor |35 so as to 'in-uence the rotormagnetically as it rotates.

Movement of the rack gears |41 and |48 occurs when the lever |55 israised. The lever |55 is attached to the shaft |56 so that as the lever|55 moves upward it causes the shaft |56 to rotate in a counterclockwisedirection, at the same time turning the gear |51 in a counter-clockwisedirection, since the gear |51 is also attached to the shaft |55. Therack gear |41 extends from the pivotal point |49 to a position above thegear |51 and has teeth which engage the top teeth of the gear |51; inlike manner, the rack gear |48 extends to a position below the gear |51and has teeth engaging the bottom teeth of the gear |51. Thus, as thegear |51 rotates in a counterclockwise direction, it causes the rackgear |41 to move to the left, which in turn pushes the feeler leversl|23 through |28, inclusive, against the periphery of the disc |2|.Similarly, the rack gear |48 moves to the right and pushes the feelerlevers ,|29 through |34, inclusive, linto contact with the disc 20|shown in the cut-away view of the discs in Fig. 2. If the signallingtransmitter were to be used in connection with telephone work, the lever|55 might come up only when the receiver is lifted from the cradle.Lifting of the lever |55 results from the fact that the spring |58 is ina compressed condition when the lever |55 is in its lowered positionand, as soon as the object holding down the lever |55, such as atelephone receiver resting in its cradle, is removed, the spring willexpand to its natural length, pushing the lever up with it. The spring|58 is fastened at one end to the table |5|, which is in turn supportedby the chassis |31, and at the other end the spring is attached to thelever |55. The stops |59 and |00 serve to limit the movement away fromthe discs |2| and 20| of the feeler levers |23 through |28 and |29through |34, respectively, when the lever |55 is again lowered. Fig. 2shows the lever |55 in its raised position and further illustrates howthe rack gears |41 and |48 are moved in their slots so that the feelerlevers will be made to touch the periphery of the discs |2| and 20|. Aselective movement of certain of the stator pole elements results, asshown in Fig. 2.

As may be seen in Fig. 1 and also Fig. 1, selection of the particularstator elements to move t0- wards the rotor |35 is determined by theposition of the reentrant code discs |2| and 20|. Considering the codedisc |2|, the irregularities on the disc are arranged in a distinctivepattern around the periphery, and a certain pair of the stator poleelements in a group may be selected only when the code disc is rotatedto such a position that the feeler levers of the desired pair of statorpole elements touch corresponding raised portions of the periphery.Figs. 5, 6 and 7 illustrate one way in which the raised irregularitiesmay be located around the periphery'of a reentrant code disc. Assumingthat a two-out-of-six pattern is used to obtain distinctive combinationsof the stator pole elements in a set, Fig. 5 shows the iiiteen differentcombinations that may be obtained. In Fig. 5, six boxes are alignedhorizontally to correspond to the six individual stator elements in aset and the fifteen rows extending downward show the iteen possiblecombinations. Dots in a box indica-te that a particular stator elementhas been selected. Thus, the rst row 500 of boxes indicates that a pairof stator elements have been selected which correspond to the elements|0| and |04 in the set comprising the elements |0| through |06,inclusive; similarly, the elements |03 and |05 are the selective polesin the second row 50| of boxes and the elements |0| and |06 will bepushed towards the rotor as indicated by the dots in the third row 502of boxes. The rows 503 through 5M, inclusive, indicate the othercombinations in which two of the stator elements in a set may be locatedclose to the rotor. If, now, the periphery of the code disc were to bedivided into fifteen equal arcs and each of the fifteen arcs weredivided into six smaller segments of equal length, raised portions wouldhave to extend from two of the segments in each of the iifteen equalarcs, with each arc having raised tabs extending from a different pairof segments. Thus a total of ninety segments would have to be providedand thirty raised tabs would extend from the periphery of each disc. Ifthe discs were made smallsmall enough, for example, to fit into the baseof a telephone subset-the tabs might be too crowded to give efficientoperaticml of the disc,

Fig. 6 indicates. however. a way in which sixty segments around theperiphery of a reentrant dise could accomplish the same results as theninety segments which would ordinarily be required. As shown in Fig. 6,this is attained by causing the last two segments of one arc to overlapthe rst two segments of the next. Thus the last two segments of the arcembracing the combination shown as the numeral 600 would embrace thefirst two segments of the combination shown as 68| and in like manner,the last two segments of the combination shown as the nu.- meral 60|would embrace the first two segments of the combination shown as thenumeral 602. This overlapping of the last two segments of onecombination with the rst two segments of the next combination occurs forall of the combinations GUI through IA, inclusive, and the resultantpattern is shown as the numeral SI at the top of Fig. 6. By overlappingthe last two segments of one arc on the nrst two segments of the nextarc, the number of segments may be reduced from ninety to sixty and,additionally, the number of raised tabs may be reduced below the thirtythat would ordinarily be required. Fig. 6 illustrates that the number oftabs are reduced from thirty to twenty for the arrangement shown.

There are a number of ways in which the different combinations might bearranged around the periphery of a disc. For example, a new arrangementfrom that shown in Fig. 6 would result if the combination 602 wereplaced between the combinations and 60| instead of having thecombination between the combinations 600 and 602, as illustrated in Fig.6. Or another arrangement might be effected byplacing the combination602 iirst, the combination 600 second, and the combination 50| third. Nomatter what arrangement of the different combinations is used around theperiphery of a disc,

the periphery would have to be divided into only sixty segments providedthat the last two segments of one combination were allowed to overlapthe rst two segments of the next combina,- tion on the periphery of thecode disc. Additionally, less than thirty raised tabs would be requiredon the periphery of a dise regardless of the arrangement employed butthe actual number of raised portions required would depend upon thearrangement employed. Instead of overlapping the last two segments ofone combination on the iirst two segments of the next, as shown in Fig.6, the last three segments of one combination might be made to overlapthe rst three segments of the next combination. By this scheme, theperiphery of each disc would only have to be divided into forty-fivesegments and the number of raisedextensions would be reduced even belowthat required when two segments overlap.

Fig. 7 illustrates how av disc would appear when the overlappingarrangement of Fig. 6 is used. As shown on Fig. '7, the periphery of thedisc is divided into the fifteen equal arcs '|00 through '|I4,inclusive. The overlapping effects are shown by means of the bracketsand the positions of the tabs in the arcs are also Shown. Wherever twotabs lie next to each other on the periphery of the disc, a single tabof double width is made to appear, such as the tab. 'H5 in Fig. '7.

Although a two-out-of-six arrangement is shown for each of the setscontaining adjustably positioned pole elements, other arrangements mightbe used. Thus, for example, a threeout-of -six arrangement or atwo-out-of-seven ar- 8 rangement or any of a number of other arrangedments might be used. With a two-out-of-six arrangement in fourgenerators containing two sets each, however, a total ofYA more than2,500,000,000 different combinations is possible.

Referring again to Fig. 1, a cylinder |22 is shown as being mounted onthe same shaft |65 as the disc I2 I. This cylinder has fteen notches cutinto its periphery, corresponding to the fifteen different combinationsthat may be obtained from the two-out-of-six code. Thus, if radii aredrawn to two adjacent notches on the cylinder |22, the arc cut off onthe disc |2I would be one ofthe fteen equal arcs described above, thetabs on the arc giving an indication of one of the fifteen possiblecombinations. In order that the cylinder will not be rotated to aposition such that parts of two adjacent arcs, instead of a completearc, will be acted upon, a latch |66 extends from the top of the chassis|31. The latch |66 acts as a detent to engage a notch, such as the notch|61, on the cylinder |22, so that a complete arc of the dise will beacted upon by the feeler levers. If now, each or the arcs on thecylinder |22v is numbered or lettered to identify it from the other arcson the cylinder, a particular arc may be chosen by rotating the cylinderby hand until the numeral or letter corresponding to the particular arcmay be seen by looking down upon the chassis I3? from above. A slot iscut in the chassis |3i so that the cylinder may extend above the chassisand thus be manually operated from a position outside of the chassis.

In addition to the stator elementsA on each generator for sending out acalling signal and the stator elements for sending out a signal toidentify the calling transmitter, a set of stator elements is providedon each generator for send'- ing out a start signal. When thetransmitter begins to transmit, the start signal will be the firstsignal to be sent out and will serve as a warning to the variousreceiving stations that the code signal is about to be transmitted.Since the start signal serves only as a warning signal and is notincluded in the coded signals for calling a particular station or foridentifying the calling station, it should not have the same codepattern as these other signals. Thus, whereas two-out-of-six andtwo-out-of-ive patterns are chosen as the calling and identifying codes,a solid block pattern of three-out-of-three may be chosen to serve asthe code for the warning signal. This pattern results from placing threeadjacent stator pole elements in sufficient proximity to the rotor so asto be coupled magnetically to the rotating generator pole. Thus, thestator pole elements IIB, IIS and |20 shown in Fig. l are placed nearthe rotor |35 to serve as the means for attaining the start signal. Aswith the pole elements II3 through II'I, inclusive, for obtaining theidentifying signal, they stator poles IIS, I I9 and IMlA are maintainedin fixed position by means o bolts or rivets.

Since each generator is sending out signals simultaneously will all ofthe other generators comprising the transmitter, and since thetwoout-of-six pattern is used for each generator, the pair of pulsessent out by each set of stator elements on a generator would fuse intoan indistinguishable jumble of pulses if each generator operated at thesame frequency. Different frequencies for the generators ofa transmitterare obtained by varying the number of notches, 0r teeth, on the statorelements of each generator. Because of the fact that the generators arecoupledA to the same shaft, they will rotate at the same speed and thusthe frequencies they transmit will be proportional to the number ofnotched poles cut into their stator elements on that side of the statorfacing the rotor. Thus the stator elementson the generator shown inFigs. 1 and 2 all have ve notches cut into them. The stator elements ofthe other three generators comprising the transmitter shown in Fig. 3might have 3, '1 and 9 notches respectively, yielding proportionalfrequencies for the four generators of 3:5:1:9. The notches cause thevoltage inducted in the rotor coil when passing a stator element to varyfrom a maximum value, when the rotor faces a peak between two notches,to a minimum value at the trough of the notch, and this constantvariation between maximum and minimum values results in an alternatingvoltage being induced in the rotor winding |39. Since the four codedsignals transmitted at one time all have diiierent frequencies, theyvmay be easily separated at the receiving end.- Ihe signals which followthe rst group of signals will have the same frequencies as the lirstgroup of signals but these signals may be distinguished from the iirstsignals by the elapsed time element between them.

Referring now to Fig. 3, which is a front View of the transmitter asopposed to the side views of Figs.f1 and 2, a View is shown of thecomplete signalling transmitter, which consists essentially of aplurality-four as shown in Fig. 3-of generators similar to the generatordescribed in connection with Figs. l and 2. One of the generators, thegenerator 300 at the bottom right of Fig.v 3, is shown with its rotor30|, which is similar to the rotor |35'of Fig. 1. The stator poleelements 302 and 303 are positioned similar to the pole elements ||5 andH9, respectively, of Fig. 1, and are magnetically coupled to the poleelement 304 on the rotor 30|, the pole element 304 being similar to therotor pole element |63 of Fig. l. The brush 305 makes Contact with theslip ring 3,06 of the generator 300 because of the action of the bracket3|3, which is attached at one end to the chassis |31 and at the otherend to the brush 305, servingvto hold the brush 305 tightly against theslip ring 306. The rotor 30| is coupled to the shaft 301 as are therotors oi the other three generators shown in Fig. 3 and the motor 300,which drives th-e generators. The bearings 309 and 3|0 and the bracket3| I, all of which are attached to the chassis |31, help to support theweight of the shaft 301 and the rotors attached to the shaft, thebracket 3| serving as a table for the motor-308. v

The generator 3|2, which is just to the left of the generator 300,although actually constructed in a similar manner to the generator 300,

appears different from the generator 300 in Fig.` 3 because ofthe'factthat its rotor is not shown.y

rlhe stator elements3|4 and 3|5 are shown, however, as corresponding tothe stator elements 302 and 303, respectively, on the'generator 300, anda feeler lever 3|6 is shown extending down from the disc 346, similar tothe disc |2| of Fig. 1, to one of the sets of adjustable statorelements.The stator of the generator 3| 2 is attached to the chassis by means ofthe bracket 3|1 and the bolt 3|8 in a manner similar to the way in whichthe stators of the other generators are supported.

The generators 3|9 and 320 in Fig. 3 illustrate the manner in which theadjustable stator elements are located on the sides of the generatorstators and further show how the feeler levers extend down from thediscs and are fastened to Cil these stator elements. Referring to thegenerator 3|9, with the understanding that the generator 320 showssimilar features, a set of adjustable stator elements is showncomprising the stator elements 32| through 326, inclusive, these beingsimilar to the stator elements l0| through |06, inclusive, of Fig. l.ver is attached to each of these stator elements; for example, thefeeler lever 321 is attached to the stator pole element 32|, therebycontrolling the movement of this stator pole, and, in like manner, thefeeler levers 328 through 332, are attached to the stator elements 322through 326,

respectively. The feeler levers 321 through 332',- inclusive, aresimilar to the feeler levers |23- through |28, inclusive, shown in Fig.1 and extend up to a position normally near the per-iph-` ery of thedisc 333, just as the levers |23 through |28 of Fig. 1 lie near theperiphery of the disc |2|. Other levers extend from a position adjacentto the periphery of the disc 334, which lies next to the disc 333, andare fastened to the sta-- tor elements on the generator 3| 3 which liedirectly opposite the stator elements 32| through 326, inclusive. Thus,the feeler levers 335 through 340 extend from a position near the disc334 down the back side of the generator 3|9 to bracket 343 whichsupports the brush 342 to they bracket 3| Since there are two sets ofadjustable stator elements on each of the four generators and since aseparate disc is required for each set of stator elements, eight discsare shown in Fig. 3. These.

comprise the discs 333, 334, 343, 344, 345, 346,.

341 and 348. Furthermore, because of the facty that a cylinder, such asthe cylinder |22 of Fig. 1, is associated with each disc, eightcylinders are shown in Fig. 3 and these comprise the cylinders 349through 356, inclusive. Referring now to the discs 345, 346, 341, and348, these discs are represented as being individually coupled to theconcentric shafts 351, 358, 359 and 360, respectively. As may be seenfrom Fig. 3, the cylinder 356 is also coupled to the shaft 351 and thecylinders 353, 354 and 355 are coupled to the shaftsv 360, 359 and 358,respectively. Concentric shafts. are employed to save space and to allowthe cylinders 349 through 356, which. serve as .the means for visuallyindicating the signal, to be lined up in a row at the top of thechassis. TheA cylinders 349 through 356 have flanges, as illus-f tratedby Fig. 3, which extend up above the top of the transmitter chassis |31through slots cut in the chassis so that the cylinders may be moreVeasily rotated by the operator for setting up a signal number. Eachcylinder has coded identiications marked on its periphery, as may be.

seen by viewing the cylinders 349 through 352, so that as a-cylinderisturned diierent identications will appear at the top of the cylinderand will be accordingly seen by the operator as he looks down at the topof the chassis. Either the slots in the chassis may be made wide enoughto allow the coded identifications on the cylinder to be viewed or thechassis may have transpar- A separate feeler le-A ent -portionsextending across the top of the chassis at places directly above thecylinders. These coded identifications are shown las numerals in Fig. 3'but they 4may be letters of the alphabet or Words or any other codedesired. The coded v-letters may be so arranged that when a particularnumber is seen at the topmost position of the cylinder, the disc whichturns with the cylinder will be positioned to effect a movement towardsthe rotor of *the combination of stator elements corresponding to theparticular -code desired. The discs 343, 3M, 333 'and 331i are alsocoupled to concentric shafts, not shown in the drawings, and are rotatedwhen the cylinders 349, 55! and 352, which are coupled to the saineshafts, are turned. The shaft |65 serves vas a bear-ing for the'concentric shafts, and is itself held up by the supports 352 and 363,'which are -in turn attached to the transmitter chassis 31. The shaft|65is also shown in Fig. 1.

In addition to holding the shaft |65 in position, the supports 36-2 andi353 hold up the stop shafts |59 and |69. These stops limit the movementof the feeler levers away from their associated discs. Similarly, theshafts |49, |5, 15! and |52 appear as the -shaft 354 in Fig. 3. Theshafts |50 and |5| are immovable andso ar-e attached to the chassis;however, the shafts |49 and |50 move when the rack gears |41 and V| 48move and so they cannot be attached to the chassis |31. Consequently,they are fastened to slotted supports, not shown, which permit theshafts lto move in a direction perpendicular to the plane of the `paperas viewed from Fig. 3. The gears 365 and 36S appear as the vgear |51 ofFig. 1 and are enmeshed with the Araclr gears 351 and and the rack gears369 and 3170, respectively. The rack gears 361 and 389 appear as thegear |41 in Fig. 1 while the gears 358 and 31|! appear as the gear |48in Fig. A1. The levers 31| and 312 seen in vcross sec- .,j

tion in Fig. 3 are the same as the lever |55 shown in Fig. '-1, twolevers being yshown to correspond with the two cradle levers supportingthe receiver in Fig. 4.

Fig. 4 shows how va subscribers subset 400 might appear if thetransmitter were used in telephone systems. In addition to the cradlelevers 'and the receiver 40| previously mentioned, the eight cylinderswhich serve as the means for visually monitoring the calling signal areshown.

While certain specinc embodiments of the invention have been described,it should be understood 'that various other embodiments of the in-uvention 'may be made 'by those skilled in the art without departing fromthe spirit of the invention as defined, Awithin vthe scope of theappended claims.

`Whatis claimed is:

vl. A signal transmitter comprising, a rotatable shaft, a lplurality ofgenerators coupled to Ysaid shaft, a plurality of stator elementsassociated with each generator, means on said stator elements forvcausing each generator to transmit a different frequency, means foradjusting the stator elements of each 'generator whereby coded impulsesof current may be transmitted, and means connected to said rotatableshaft for -driv ing said generators.

'2. A signal transmitter comprising, a rotatable shaft, a plurality `ofgenerators coupled to said shaft, a 4plurality of Vadjustably positionedstator elements Vassociated with each generator, means on .said statorelements for causing each generator to transmit a different frequency,means `for adjusting said stator elements of each generator wherebycoded impulses of :current may be-transmitted, additional statorelements on each generator for effecting the transmission of startsignals consisting of pulses coded differently from said aforementionedcodes, and means connected to said rotatable lshaft for driving saidgenerators.

3. A signal transmitter comprising, a rotatable shaft, a plurality ofgenerators coupled to said shaft, a plurality of adjustably positionedvstator elements associated with each generator, means on said statorelements for causing each genera.- tor to transmit a differentfrequency, and means for adjusting said stator elements of eachgenerator whereby coded impulses of current `may be transmitted, furtherstator elements on 'each generator arranged to transmit coded impulsesfor identifying the particular transmitter, and means connected to Isaidrotatable shaft for driving said generator.

4. A signal transmitter comprising, a rotatable shaft, a plurality ofgenerators coupled to said shaft, a plurality of adjustably positionedstator elements associated with each generator, means on said statorelements for causing each generator to transmit a different frequency,means for adjusting said stator elements of each generator whereby codedimpulses of current may be transmitted, additional stator elements oneach generator arranged to transmit coded impulses for identifying theparticular transmitter, further stator Velements on each generator foreffecting the transmission of start signals consisting of pulses codeddifferently from'said aforementioned codes, and means .connected to said.rotatable shaft for driving said generators.

5. A signal transmitter comprising, a rotatable shaft, a plurality ofgenerators coupled to said shaft, a plurality of adjustably positionedstator elements associated with each generator, a different number ofnotches on the stator elements of each generator whereby each ygeneratoris caused to transmit a different frequency, means for .adjusting theposition of stator elements in each generator whereby coded impulses ofcurrent may be transmitted, and means connected to said rotatable shaftfor driving said generators.

6. A signal transmitter comprising, a rotatable shaft, a plurality .ofgenerators coupled to said shaft, a plurality of stator .elementsassociated with each generator, a different number of notches on thestator elements of each generator for causing each generator to transmita different frequency, means for adjusting the stator elements oi eachgenerator whereby coded impulses .of current may be transmitted,additional stator elements on each generator .arranged to transmit codedimpulses for identifying the particular signal transmitter, furtherstator' elements on each generator for effecting the transmission ofstart signals consisting of pulses coded differently from saidaforementioned code, and means connected to said rotatable shaft fordriving said generators.

7. A signaling device comprising, a rotatable shaft, a plurality ofgenerators coupled to 'said shaft, a plurality of adjustable statorelements associated with each generator, means on said stator elementsfor causing each generator to transmit a different frequency, aplurality of discs, irregularities around the peripheries of said discs,means for rotating said discs in accordance with the code to betransmitted, means for adjusting the positions of said stator elementsin accordance -with lthe position of said irregulari- 13 ties on saiddiscs, and means connected to said rotatable shaft for driving saidgenerators.

8. A signal transmitter comprising, a rotatable shaft, a plurality ofgenerators coupled to said shaft, a plurality of adjustable statorelements associated with each generator, a different number of notcheson the stator elements of each generator for causing each generator totransmit a different frequency, a plurality of discs, irregularities incoded relation around the peripheries of said discs, means for rotatingsaid discs in accordance with the code to be transmitted, means foradjusting the positions of said stator elements in accordance with thepositions of irregularities on said discs, and means connected to saidrotatable shaft for driving said generators.

9. A signal transmitter comprising, a rotatable shaft, a plurality ofgenerators coupled to said shaft, a plurality of stator elementsassociated with each generator, means on said stator e1ements wherebyeach generator transmits a different frequency, a coded discindividually associated with each generator, means for rotating each ofsaid discs into a position dependent upon the code to be transmitted,means for adjusting the positions of said stator elements in accordancewith the coded information on said discs, and means connected to saidrotatable shaft for driving said generators.

10. A disc having irregularities extending from its periphery in a codedarrangement, a generator having a stator and a rotor, a plurality ofadjustabIy-positioned stator elements located around the circumferenceof said stator, a separate lever attached to each of said statorelements and extending to a position in proximity to the periphery ofsaid disc, and means for displacing said levers into contact with theperiphery of said disc whereby the stator elements attached to leverscontacting irregularities are moved towards said rotor.`

l1. A disc having irregularities extending from its periphery in a codedarrangement a generator having a stator and a rotor, a plurality ofadjustably-positioned statorA elements located around the circumferenceof said stator, a plufrality of levers attached to said stator' elementsand extending to positions in proximity to the periphery of said disc, acylindrical gear, a rack gear having teeth enmeshing the teeth of saidgear, and means for rotating said cylindrical gear whereby said leversare displaced by said rack gear into contact with the periphery of saiddisc and thereby the stator elements attached to levers touchingirregularities on said disc are moved towards the rotor of saidgenerator.

l2. A disc, a generator for converting coded information, a number ofequal arcs arranged to overlap each other around the periphery of thedisc, and a plurality of irregularities arranged in a distinctivepattern for each overlapped arc whereby the coded informationtransmitted by said generator is determined by the rotational positionof said irregularities.

WARREN A. MARRISON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,204,759 Hubbard June 18, 19402,206,538 Rhodes July 2, 1940 2,279,232 Graham Apr. 7, 1942 2,303,918Dimond Dec. 1. 1942 2,307,965 Shepherd Jan. 12, 1943 2,388,313 DoweyNov. 6, 1945 2,418,836 Hawes Apr. 15, 1947

